Radwanska, who is the top seed at this event, reeled off four aces and converted on 6-of-10 break chances en route to a 6-4, 6-3 victory over Kimiko Date-Krumm of Japan.

Li, the 2011 Sydney champ, dropped just one game during a dominant 6-1, 6-0
decision over Japanese qualifier Ayumi Morita to advance to the quarterfinals.

Morita capitalized on her only break opportunity, but also had a pair of
double faults and allowed the fourth-seeded Li to break her serve six times.

Wozniacki, however, dropped a hard-fought 7-6 (7-4), 1-6, 6-2 decision to
Svetlana Kuznetsova in a nearly three-hour match, as the Russian ripped off
seven aces and was aided by five double faults by Wozniacki.

No. 3 seed Sara Errani of Italy cruised to an easy win with a 6-1, 6-1
decision over Russia's Maria Kirilenko, while Germany's No. 2 seed Angelique
Kerber had a little more resistance during a 6-2, 7-5 win over Kazakhstan's
Galina Voskoboeva.

American qualifier Madison Keys followed her stunning victory over Czech
veteran Lucie Safarova in the opening round with a 6-0, 6-4 win over China's
Jie Zheng.